In our laboratory, we have provided evidence that high M. W. RNA can be sequestered into negatively charged lipid vesicles (liposomes) where it is protected from the action of ribonuclease. Liposomally inserted rabbit globin mRNA in HEp-2 cells is faithfully translated with good efficiency. The parameters that maximize delivery of liposomally sequestered mRNA into eukaryotic cells have been recently determined by us. We plan to improve this system by determining if the efficiency of globin mRNA translation can be applied to other messages and cell types. Experimental evidence suggests that modulation of posttranscriptional events might regulate the turnover rate, the ribosome binding and the translational efficiency of mRNA. The evidence available was obtained mostly in cell free systems that may not faithfully represent the conditions prevailing in the intact cell. We want to ascertain in our system whether mRNA's of different phylogenetic and ontogenetic origin are translated with comparable efficiency in different eukaryotic cells. To this effect, the ability of cells to translate k-light chain, globin and albumin mRNAs will be assessed. Myeloma, HEp-2 and W1-38 human embryonic nontransformed cells will be used. The ability of mammalian cells to translate mRNA from a phylogenetically distant organism (yeast) will be assessed. Any differences in translational efficiency in different mRNA-cell systems might be due to differences in the stability and ribosome binding of mRNA or in the turnover rate of the product. Each of these possibilities will be independently investigated by studying the fate of 32P-mRNA and 125I-proteins inserted into cells. The translational efficiency, the ribosome binding and the turnover rate of mRNA deprived of either 5' mG "cap" or 3' poly a will be assessed, By these experiments we plan to test the hypothesis that cells of different origin can differentially translate mRNA's.